Neurological stimulators have been developed to treat pain, movement disorders, functional disorders, spasticity, cancer, cardiac disorders, and various other medical conditions. Implantable neurological stimulation systems generally have an implantable pulse generator and one or more leads that deliver electrical pulses to neurological tissue or muscle tissue. For example, several neurological stimulation systems for spinal cord stimulation (SCS) have cylindrical leads that include a lead body with a circular cross-sectional shape and multiple conductive rings spaced apart from each other at the distal end of the lead body. The conductive rings operate as individual electrodes and the SCS leads are typically implanted either surgically or percutaneously through a large needle inserted into the epidural space, with or without the assistance of a stylet.
Once implanted, the pulse generator applies electrical pulses to the electrodes, which in turn modify the function of the patient's nervous system, such as by altering the patient's responsiveness to sensory stimuli and/or altering the patient's motor-circuit output. During pain treatment, the pulse generator applies electrical pulses to the electrodes, which in turn can generate sensations that mask or otherwise alter the patient's sensation of pain. For example, in many cases, patients report a tingling or paresthesia that is perceived as more pleasant and/or less uncomfortable than the underlying pain sensation. In other cases, the patients can report pain relief without paresthesia or other sensations.
In any of the foregoing systems, it is important for the practitioner to accurately position the stimulator in order to provide effective therapy. One approach to accurately positioning the stimulator is to implant the stimulator in a surgical procedure so that the practitioner has a clear visual access to the implantation site. However, many patients and practitioners wish to avoid the invasiveness and associated likelihood for complications typical of a surgical procedure. Accordingly, many patients and practitioners prefer a less invasive (e.g., percutaneous) implantation technique. With a percutaneous approach, the practitioner typically is unable to see exactly where the device is positioned because the device is beneath the patient's skin and in most SCS cases, within the patient's spinal column. In addition, the process typically requires the patient to provide feedback to the practitioner based on that patient's sensations. Accordingly, the industry has developed a variety of techniques for visualizing medical devices and anatomical features below the patient's skin as the device is implanted. Such techniques include fluoroscopy, which is commonly used to aid the practitioner when implanting SCS leads. However, a drawback with fluoroscopy is that it results in added expense to the SCS implantation procedure, it may be cumbersome to implement, it limits the implantation procedure to sites with fluoroscopy equipment, and it exposes the patient to unwanted x-ray radiation. Accordingly, there remains a need in the art for improved visualization techniques that can be used to implant patient devices with greater ease, accuracy, and lower cost.